1. Field of the Invention
The present invention relates to a technique for capturing an image of a partially lustrous subject.
2. Description of the Related Art
It is very difficult to capture images of metallic lustrous subjects such as folding screens (byobu) or sliding screens (fusuma) coated with gold leaf. Image capturing of such a metallic lustrous subject is similar to image capturing of a mirror. Accordingly, if image capturing of a metallic lustrous subject is performed, a portion at which light emitted from a light source is reflected is present in a captured image of the subject. In this case, the color and gradation of the captured image of the subject differs from the actual color and gradation of the subject.
For example, if light is emitted toward a metallic lustrous subject from the front side of the subject at the time of image capturing, high-intensity light specularly reflected from the subject enters a camera and a portion having a color of a light source is present in a captured image of the subject. On the other hand, if light is emitted toward a metallic lustrous subject from an oblique direction with respect to the subject at the time of image capturing, the color of a metallic luminous surface of the subject can be accurately reproduced, but a gradation characteristic is reduced and a captured image of the subject loses a metallic luster.
A method of capturing an image of a metallic lustrous subject using two light sources has been proposed (see, Japanese Patent Laid-Open No. 05-80394). Light emitted from one of these light sources is transmitted to the subject from the front side of the subject via a screen having a white diffusion effect so as to illuminate the subject with white light. Strobe light emitted from the other one of these light sources is directly transmitted to the subject from an oblique direction without using a screen. In order to reproduce the color, gradation, and luster of the subject, lights transmitted from two directions are combined.
However, in such a method of combining lights transmitted from two directions and performing image capturing using the combined light, if the positional relationship between these light sources or the combination ratio between lights from these light sources varies, the state of a metallic lustrous surface of the subject varies widely. If lights transmitted from two directions are combined, the effects of the lights may cancel each other. Accordingly, if a desirable image cannot be captured, it is required to repeatedly change the positional relationship between these light sources or the combination ratio between lights transmitted from these light sources until a desirable image can be obtained.